They came across some boys who were being rude and abusive. These boys began to throw stones and tease the disciple, calling him names. This went on for some time as the boys followed the master and the disciple. They came to a river. The master and the disciple got into a boat in order to cross over.
The boys got into another boat and continued to bully. As they reached the middle of the river the boat began to capsize. The master slapped the disciple across the face. The disciple was taken aback by this gesture of his Master. He had not said a word to the boys in response to their taunts. He thought he had been a good disciple and yet the master had slapped him!
The master said, “It is your fault. You are responsible for their boat sinking. You did not respond to their abuse, which would have taken their karma away. Nature has now punished them in a worse way because you did not have enough compassion to quell their insults.”
With that slap the master took away the karma of this event so that it would not be carried into the boys’ future. It also served to take away any little bit of joy the disciple may have felt at seeing the boys’ boat sink. Thus, it also took away the karma of the event for the disciple. So the anger of the enlightened is a blessing.